I think your suggestion was too vague. You don’t even have to go to the extreme and ask him “do you want to be in a relationship”. You’re just hooking up, and I think you should date first before asking questions like that. Just ask him out. Like find out when he’s free and then ask “ do you want to go see a movie this weekend, or do you want to go to dinner or have coffee”. And if he makes up an excuse then you know he’s not that into you.
But I would just like to let you know that you may not be the only one he’s hooking up with. So I would not put all my hopes onto this but it’s worth a try.